I have exeperince with both, and no doubt both are a decent mud/street tire.
Kumhos over the Dunlops, I say this because of their longetivity, and funcunality; the kumhos grabbed a little better in the mud as the tread helps toss the mud instead of it getting 'stuck' in the tread, leaving you stuck in a mud hole. Also i experinced that the Kumhos were quieter on the street for longer (as they get worn in). All in all, they both eventually make vibrations and chop. Kumhos seemed to be a notch higher in quality, but again thats my opinion, they both will take the abuse.
they are pretty close, go with whatever is cheaper